The present invention relates to a continuous mixing plant, and more particularly to a continuous mixing plant that is suitable for continuously producing concrete for a short period of time simply by, for example, continuously feeding necessary material while measuring it and dropping the material by gravitational force.
Conventionally, a batcher plant that is an apparatus for producing concrete is equipment for mixing cement, water, sand, rough sand, mixer agent and the like for the material of the concrete measured in a predetermined composition for producing the concrete that is kept in non-solid condition, and has been widely used in a dam construction, a civil construction, a green concrete factory, a concrete secondary factory or the like.
The conventional batcher plant is roughly composed of a material reservoir portion, a metering portion, a kneading portion and a loading portion. The batcher plants are divided into various types in accordance with these arrangements. The most typical system is of a tower type as shown in FIG. 11. The conventional tower type batcher plant 1 shown in FIG. 11 is a system in which a receiving chamber 2, a material reservoir 3 (a cement reservoir 3a, a sand reservoir 3b, a small stone reservoir 3c, a water reservoir 3d), a metering portion 4 (a cement metering tank 4a, a sand metering tank 4b, a small stone metering tank 4c), a concrete mixer 5, a concrete hopper 6 and the like are overlapped in order in a tower-like shape from above. A type in which an operating chamber 7 projects from a metering or mixer chamber 8 and a type in which an operating chamber 7 is separated from the plant are popular.
Thus, almost all of the conventional batcher plants including that shown in FIG. 11 are of a batch processing type (the process in which a predetermined amount of materials is mixed and agitated every time, and this is repeated). Then, one for metering and agitating the materials for every turn is called a batch mixer.
However, in such a batch process, the manufacture of concrete is intermittent and such a process is not so effective for continuously producing a large amount of concrete. For this reason, in the conventional tower type batcher plant 1 as shown in FIG. 11, two concrete mixers 5 are arranged within the mixer chamber 8, and these are alternately used in order to keep the continuation or continuity of the concrete manufacture as much as possible.
Even in a batch process, if the plurality of concrete mixers 5 are arranged as described above and are used in order, it is possible to keep continuous manufacture to some extent. However, there is a problem that the more the number of the installed mixers 5, the larger the equipment of the batcher plant as a whole will become.
By the way, it is desired to continuously perform the manufacture of concrete in this manner. It is however very difficult to continuously mix the materials in an optimal manner. Actually, a mixing apparatus, i.e., a mixer that is actually usable effectively has not yet been realized. Also, even if such a continuous mixer is developed, there is a problem as to how the amount of each material to be continuously introduced into the mixer is metered for manufacturing a high quality concrete. Also in view of this point, it is considered impossible to perform the effective continuous manufacture of concrete.
In order to overcome the above-described problems inherent in the prior art, an object of the present invention is to provide a continuous mixing plant that, for example, simply continuously feeds the necessary materials while metering the amount thereof and drops these materials by gravitational force so that the mixed material may be manufactured continuously for a short period of time suitably, and in the case where the mixed material is concrete, it is possible to manufacture higher quality concrete continuously for a short period of time while accurately continuously metering each material and feeding it to the mixer.
The present invention relates to a continuous mixing plant. In order to solve the above-described problems, the invention is constituted as follows. Namely, according to the present invention, there is provided a continuous metering and feeding means for keeping on feeding at least two kinds of materials to be mixed with each other while continuously metering the materials, the number of the continuous metering and feeding means being the number corresponding to the materials, and at least one mixing box unit for mixing the materials fed continuously from the continuous metering and feeding means, characterized in that the mixing box unit is provided with: a plurality of modified passages each of which has an inlet at one end and an outlet at the other end, a cross-sectional shape of which is continuously changed from the inlet toward the outlet and which extend in an axial direction; and a merging and dividing means provided between the inlet and the outlet of each of the modified passages for merging and dividing each material passing through each of the modified passages, and each material is continuously cast from the inlet portion and passed toward the outlet portion through each of the modified passages by the gravitational force to be mixed.
In the continuous mixing plant according to the present invention, it is preferable that the plant further comprises a metering means for metering a delivery amount locally and for every predetermined time in a midway for continuously delivering the material fed from each of the continuous metering and feeding means, and the continuous metering and feeding means receives a signal from this metering means to be feedback-controlled, thereby enhancing precision of the material supply amount.
In such a continuous mixing plant, at least two materials to be mixed are an aggregate and mortar, or cement paste, and the mixing plant is applied as a plant for continuously manufacturing concrete.
A continuous mixing plant according to the present invention may further take the following structure. Namely, there is provided a continuous mixing plant comprising a main belt conveyor unit for delivering aggregate; a continuous aggregate feeding means for keeping on feeding at least one kind of aggregate to the main belt conveyor unit while metering the material; a first detecting unit installed downstream of a delivery belt of the main belt conveyor unit for metering continuously at a predetermined position a local amount of the aggregate that has been transferred on the delivery belt of the main belt conveyor unit, thereby outputting a signal; a continuous fixed amount supply means installed downstream of the main belt conveyor unit having the aggregate fed for keeping on feeding a fixed amount of mortar or cement paste continuously to the main belt conveyor unit; and at least one mixing box unit disposed just below a delivery end of the main belt conveyor unit, characterized in that the continuous fixed amount supply unit receives the signal continuously output from the first detecting unit and is feedback-controlled to enhance precision of the supply amount of the mortar or cement paste, and that, furthermore the mixing box unit is provided with: a plurality of modified passages each of which has an inlet portion at one end and an outlet portion at the other end, a cross-sectional shape of which is continuously changed from the inlet portion toward the outlet portion, and which extend in an axial direction; and a merging and dividing means provided between the inlet portion and the outlet portion of each of the modified passages for merging and dividing concrete passing through each of the modified passages and concrete is cast from the inlet portion and passed toward the outlet portion through each of the modified passages by the gravitational force to be mixed.
Although the continuous mixing plant according to the present invention comprises the above-described necessary structural elements, it is possible to establish the invention even when the structural elements are specifically as follows. Namely, the continuous aggregate feeding means includes: a belt conveyor unit for feeding the aggregate to the main conveyor unit; a material delivering unit for continuously feeding the aggregate to the belt conveyor unit; and a second detecting unit installed downstream of the belt conveyor unit so as to output a signal by continuously metering at a predetermined position an amount of the aggregate that is transferred on the delivery belt of the belt conveyor unit, the material delivering unit being feedback-controlled upon receiving the signal continuously outputted from the second detecting unit, to thereby enhance precision of the supply amount of the aggregate delivered and fed to the belt conveyor unit.
Also, the continuous mixing plant according to the present invention is characterized in that the material delivering unit includes a vibrating feeder, and a frequency of the vibrating feeder is changed on the basis of the signal continuously output from the second detecting unit to feedback-control the cutting amount of the aggregate to the belt conveyor unit.
Furthermore, the continuous mixing plant according to the present invention is characterized in that one or both of the first and second detecting units are composed of a belt scale unit for continuously metering a weight of the delivery belt as a whole at a predetermined position.
Furthermore, the continuous mixing plant according to the present invention is characterized in that the mixing box unit is constituted by connecting a plurality of elements substantially in a vertical direction, each of the elements is provided with an inlet end, an outlet end and the plurality of modified passages stretching from the inlet end to the outlet end, the inlet of each of the modified passages formed at the inlet end and the outlet of each of the modified passages formed at the outlet end have different arrangement patterns, furthermore, each adjacent elements are connected in intimate contact with each other at the outlet end and the inlet end, and a joint portion between the inlet and the outlet of each of the modified passages on the end portion of the joint side of each of the elements constitutes the merging and dividing means.
Incidentally, in the continuous mixing plant according to the present invention, it is preferable that the elements are provided with rectangular openings being arranged on the right and left sides as an arrangement pattern of the inlet of each of the modified passages and with rectangular openings being arranged vertically as an arrangement pattern of the outlet of each of the modified passages, and are constituted of at least two kinds to differentiate the communication state between each inlet and each outlet of each of the modified passages, and the mixing box unit is constituted by connecting alternately the different kinds of the elements with each other in the vertical direction.
In the continuous mixing plant according to the present invention, it is preferable that an openable/closeable cut gate is provided at an outlet of the lowermost element constituting the mixing box unit, and a discharge amount of material dropping by a gravitational force is adjusted, whereby control of a filling rate of the material in the modified passage of each element of the mixing box unit is performed.
In the thus structured continuous mixing plant according to the present invention, each material is fed continuously from the continuous supply means while being metered and caused to fall into the mixing box unit. Namely, when each material is continuously cast into the plurality of the modified passages on the inside from the inlet end located above the mixing box unit, the material is caused to fall through each modified passage by the gravitational force.
Each modified passage has a cross-sectional shape continuously varying in its longitudinal direction. The material falling through this modified passage is subjected to a compressive deformation effect and is mixed. In addition, the material passing through each modified passage is merged by passing through the dividing and merging means during a fall through this modified passage. Then, the material is divided (division) into each modified passage and falls. Preferably, this is repeated to perform the good mixture.
In such a mixing box unit, in general, a plurality of elements are connected with each other so as to overlap in the vertical direction and thus, a dividing and merging effect can be inevitably obtained. The element is provided with an inlet end, an outlet end and a plurality of modified passages from the inlet end to the outlet end. The arrangement pattern of the inlet of each of the modified passages formed in the inlet end is different from the arrangement pattern of the outlet of each of the modified passages formed in the outlet end.
If the elements are connected to each other in intimate contact with each other at the outlet end and the inlet end of the adjacent elements, the joint portion of the inlet and the outlet of each of the modified passages of each element forms the merging and dividing means. Incidentally, in the case where the element in which the rectangular openings are arranged on the right and left as the arrangement pattern of the inlet of each of the modified passages and the rectangular openings are arranged vertically as the arrangement pattern of the outlet is used, if at least two kinds of elements that have different communication states between each inlet and each outlet of each of the modified passages are prepared and the different kinds of elements are connected in the vertical direction alternately to form the mixing box unit, the linear communication portion from the upper inlet end to the lower outlet end of the mixing box unit is shortened or eliminated whereby the mixture effect of the falling material is enhanced.
For instance, this continuous mixing plant may be used as a plant for manufacturing the concrete. In this case, in particular, to obtain a high quality concrete, it is preferable that the supply amount of the aggregate to be fed from the material delivering unit constituting the continuous aggregate feeding means is detected by the detecting unit to perform the feedback control to enhance the precision of the supply amount. Alternately, in the case where at least one kind of aggregate is fed to the mixing box unit by the main conveyor unit, it is preferable that the amount of the aggregate to be continuously fed by the main conveyor unit is detected in order by the detecting unit so as to feed the mortar or cement paste from the continuous fixed amount supply unit to the main conveyor unit.